Refer to FIG. 1. FIG. 1 illustrates a cross-sectional view of a conventional light-emitting diode device. The light-emitting diode device 100 mainly includes a luminous body 102, a colloid 104 and a plastic case 106. The luminous body 102 is disposed on a bottom surface 110 of a hole 108 of the plastic case 106, and is typically disposed on a central region of the bottom surface 110. The colloid 104 fills up the hole 108 and encapsulates the whole luminous body 102.
In the light-emitting diode device 100, the plastic case 106 is usually made of polycarbonate (PC). A color of the plastic case 106 is white for reflecting light 112 emitted by the luminous body 102 toward an inner surface 116 of the hole 108 of the plastic case 106, such that the lateral light 112 emitted by the luminous body 102 can be extracted from a light-emitting surface 114 of the light-emitting diode device 100.
However, when the light 112 of the luminous body 102 is emitted onto the inner surface 116 of the hole 108 of the plastic case 106, the energy of the light 112 is decayed. Therefore, after being reflected by the plastic case 106, the brightness of the light 112 is decreased. Furthermore, with such a design, a light field of the light-emitting diode device 100 is limited by an opening design of the plastic case 106.